The invention relates to the field of electrical energy supply engineering. The invention relates to in particular a transformerless cycloconverter for connecting a first three-conductor system to a second three-conductor system as claimed in claim 1.
Using a transformerless cycloconverter, electrical energy can be transferred between conductor systems which have, for example, different rated voltages or, in the case of AC voltage, different frequencies. This can be implemented by the use of bridge modules having electronic semiconductor switches without expensive and complex transformers. It is already known, for example, to connect the intermediate circuits of two converters to one another (back-to-back configuration), wherein the first converter is connected to a first three-conductor system and the second converter is connected to a second three-conductor system. If a modular converter is used as converter, in total twelve bridge modules or series arrangements thereof are required for this. Likewise, it has already been proposed to connect a first three-conductor system to a second three-conductor system via a matrix-like arrangement of nine bridge modules or series arrangements thereof.
The invention is therefore based on the object of enabling simpler and more cost-effective coupling and direct conversion between two three-conductor systems.